[Solution]
As of 24:00 on December 26, a total of 635 local confirmed cases have been reported in this round of Xi'an epidemic, and the number of confirmed cases has become the largest number of confirmed cases in a single place after the Wuhan epidemic.
The source of the epidemic and its transmission path have not yet been fully understood. On December 26, the honorary chief editor of the Phoenix News client, Tang Baihu, said that one of the transmission routes of this round of Xi'an epidemic is Xi'an Xianyang International Airport (hereinafter referred to as "Xianyang Airport"). ”) of the air supply system.
Tang Bohu said that the terminal T3 of Xianyang Airport has carried out an improvement study on the end cooling and heating form of the HVAC system, combining the floor radiant heating and cooling with the downward air supply structure, which leads to the downward air supply structure. The return air "pneumatic poisoning" caused the virus originally located in the waiting area on the first floor of the International North Corridor to be pumped to the waiting area on the second floor more than 200 meters away. Four patients infected at Xianyang Airport were sent by air pipes. new coronavirus infection.
However, this claim was subsequently questioned. Liu Xiaohua, a professor at the School of Architecture at Tsinghua University, told Jiemian News that the air-conditioning design of Xi'an Xianyang Airport would not lead to the spread of the new coronavirus.
Liu Xiaohua once participated in the design of the air-conditioning system of the T3 terminal of Xi'an Xianyang Airport. She also introduced to Jiemian News that the check-in hall of the terminal adopts the air-conditioning form of "radiant floor + replacement air supply". In winter, radiant floor heating is adopted, and the "displacement air supply" is sent into the room with filtered and heated outdoor fresh air, and the hot air flows directly upwards, and there is no return air for reuse. Compared with the traditional "one-time return air full air" air conditioner, the air conditioner in the airport's check-in hall has a lower possibility of virus infection.
Public information shows that the air conditioning system of Xianyang Airport T3A terminal has been improved to achieve energy conservation and emission reduction, and Zhou Min, chief engineer of China Northwest Architecture Design and Research Institute Co., Ltd., is in charge of the design of the expansion project of the T3 terminal area. Zhou Min has previously publicly introduced that the airport uses radiant cooling and heating + displacement down-air supply or radiant cooling and heating + dry coil air conditioning + displacement (fresh air) down-flow, and the system is approved by Tsinghua University. Building energy efficiency research center test.
Professor Zhu Yingxin from the School of Architecture of Tsinghua University also told Jiemian News that the new air conditioning system at Xianyang Airport has no return air. Even in other terminals with traditional central air conditioning systems, the possibility of new coronavirus infection caused by circulating air is very low. The above air-conditioning design will not cause the new coronavirus to spread from the international flight area of Xianyang Airport Terminal T3A to the domestic flight area.
Zhu Yingxin said that in the traditional air-conditioning system, the cooling and heating needs to be completed by circulating air, but the new air-conditioning system adopted by Xi'an Xianyang Airport uses the floor for cooling and heating, and the fresh air system is supplied with fresh air in the form of air supply below. Ensure personnel hygiene requirements, and no return air.
In this new system of Xianyang Airport, the fresh air supply only needs to ensure the hygiene requirements, so the air volume is not large, and the purpose of the downward air supply is to directly send the fresh air into the personnel stay area. In addition, in summer, the fresh air also needs to undertake the task of dehumidification. The fresh air is dehumidified by salt solutions such as lithium chloride or calcium chloride, and the salt solution will kill viruses and bacteria.
The previous papers by Zhou Min, Liu Xiaohua and others on the air-conditioning system of Xianyang Airport
More importantly, Zhu Yingxin said that the terminal building of Xianyang Airport is huge, with dozens or even dozens of corridors. Each corridor will use an independent air-conditioning system. Multiple air-conditioning systems provide services, and different corridors will not use the same set of air-conditioning systems, let alone the international and domestic areas that are far away. Therefore, even if a traditional air-conditioning system with return air is used, it is impossible for the new coronavirus to run from the international area to the domestic area through the air-conditioning duct.
Therefore, not only does the air in the international flight area and the domestic flight area do not flow each other, but also the air flow between different corridors in a single area is independent of each other.
Therefore, Zhu Yingxin said that even if there is a new crown virus at Xianyang Airport, it is impossible for the air-conditioning system to directly send the virus from the international area to the domestic area. "According to the requirements of fire prevention and smoke prevention, the air conditioning system cannot cross the fire compartment. The service scope of an air conditioning system is limited, and it must be served nearby. This is the basic principle of air conditioning system design. If long-distance transportation is carried out, not only the air duct will be very thick, and it will occupy more space. The space is very large, and it will lead to huge energy consumption of the fan." Zhu Yingxin said.
In addition, Tang Bohu also pointed out that two of the confirmed cases used the toilet near the check-in counter, which has the possibility of transmission and infection. "A very small amount of exhaled virus particles are inhaled through the return air outlet, and then diffused through a large range of pneumatic pipes, and finally diffused through the bathroom air outlet at the other end of the terminal building. Finally, they have to be contaminated and enter the infected person's nasal cavity."
The restroom has its own internal exhaust system, which only exhausts air to the outside, not to the common areas. The toilet exhaust fan will run continuously, so that the toilet is in a negative pressure state, which is lower than the air pressure in the public area, and the public area will supply air to the toilet through the door of the toilet. Therefore, the polluted air from the toilet does not enter the public area.
It is also worth mentioning that the above-mentioned experts all said that if it is indeed the return air system that causes the circulation of the new coronavirus, then Xianyang Airport will not be infected with only four people. From this perspective, the possibility of the spread of the new crown caused by the air-conditioning system can also be ruled out. sex.
Up to now, there have been few cases of new crown transmission caused by air conditioning systems in the world. The above-mentioned experts said that even in other airports using traditional central air conditioning systems, the possibility of circulating new crown virus infection is very low.
Liu Xiaohua told Jiemian News that the return air system of the air conditioner will have filtering means, and since the emergence of the new crown epidemic, the traffic station buildings have adopted the fresh air operation system, that is, the fresh air and indoor circulating air are no longer mixed together. After filtering, it is sent back to the room, but directly "cut off" the return air system to reduce circulation.
Zhu Yingxin also said that in fact, since the "SARS" epidemic, the air conditioning systems of all airports will ensure sufficient ventilation to dilute the possible viruses. Liu Xiaohua also added that the gates of airport terminals are often opened due to passengers entering and leaving. The actual measurement results of many airports show that the amount of fresh air entering through opening the gates in winter has exceeded the mechanical fresh air volume designed by the air conditioner; the floor height of the airport is also higher than that of office buildings, Areas such as residences, therefore, compared with relatively confined small spaces, from the perspective of air circulation, the possibility of the spread of the new coronavirus at the airport is also lower.
(The full text is from "Interface News", only for sharing and communication, does not represent our point of view, invaded and deleted)
